#F3F9FF

CSS

:root {
  --cotton-ball: #f3f9ff;
  --cotton-ball-rgb: 243 249 255;
  --cotton-ball-oklch: oklch(0.979 0.01 247.9);
}

.element {
  color: var(--cotton-ball);
  background-color: hsl(210 100% 98%);
  border-color: oklch(0.979 0.01 247.9);
}

Tailwind CSS v4

@theme {
  --color-cotton-ball: #f3f9ff;
  --color-cotton-ball-50: #f3f5f8;
  --color-cotton-ball-100: #e5e8eb;
  --color-cotton-ball-200: #d1d5d8;
  --color-cotton-ball-300: #b3b8bc;
  --color-cotton-ball-400: #9a9fa4;
  --color-cotton-ball-500: #81878d;
  --color-cotton-ball-600: #6d7277;
  --color-cotton-ball-700: #575b5f;
  --color-cotton-ball-800: #404346;
  --color-cotton-ball-900: #2c2e30;
  --color-cotton-ball-950: #191b1d;
}

SCSS

$cotton-ball: #f3f9ff;
$cotton-ball-rgb: 243, 249, 255;
$cotton-ball-light: mix(#fff, $cotton-ball, 20%);
$cotton-ball-dark: mix(#000, $cotton-ball, 20%);

.element {
  color: $cotton-ball;
  box-shadow: 0 0 0 2px rgba($cotton-ball, 0.35);
}